Examples of lighting apparatuses provided in a cabin of an aircraft include: lighting apparatuses provided at a floor surface of an aisle at prescribed intervals; lighting apparatuses that locally illuminate passenger seats for passengers reading books or the like; and lighting apparatuses that illuminate a ceiling above the aisle. Among these lighting apparatuses, the brightness in the cabin is mainly controlled by the lighting apparatuses that illuminate the ceiling above the aisle.
In recent years, for improvement of fuel efficiency of aircraft, not only the body of the aircraft but also various apparatuses installed in the cabin of the aircraft are required to be reduced in weight. For this purpose, a lighting apparatus for use in the cabin of an aircraft, which adopts LEDs as light sources, has been known (refer to Patent Document 1, for example). In particular, many lighting apparatuses for illuminating the ceiling above the aisle are provided over the entire length of the cabin, and therefore, using compact and lightweight LEDs as light sources of each lighting apparatus contributes to reduction in the total weight of the aircraft.
FIG. 9 is a diagram showing an example of installation of lighting apparatuses of this type. In FIG. 9, lighting apparatuses 101 and 102 are used for illuminating a ceiling C above an aisle P in a cabin of an aircraft AP, and are provided above and along one side and the other side of the aisle P, respectively. The lighting apparatuses 101 and 102 are mounted to upper ends of overhead storage bins SRp and SRw above an aisle-side seat Sp and a window-side seat Sw, respectively, so as to be invisible from passengers sitting in the seats Sp and Sw. In FIG. 9, dashed arrows indicate optical axis directions of illuminating light emitted from the lighting apparatuses 101 and 102.